Pros
The pantries are nice, although the majority of the food is basically vending machine fare. The building is constructed entirely with glass walls which is either cool or utterly fascist depending on cynical you are. Working on Solaris 10 and C++ -- and IF YOU GET INTO THE RIGHT GROUP (not GTEC, ADSK, or GSUS), you'll definitely improve your chops. Interesting mix of technologies. Lots of hot women, although chances are none will actually date you.
Cons
Allegedly flat hierarchy, but in essence the place operates as a bunch of warring fiefdoms. Compensation formulas are bizarre and based on totally unrealistic goals. A lot of green, i.e. young, managers who pay absolutely no attention to the long-term goals. Managers in particular are risk averse to the point where you're relegated to cutting and pasting the same code over and over again "because it's been in production for a year." Young workforce gleefully works 12 or 14 hour days, which becomes the dominant paradigm so those who want a balanced life or at least a parent for the child need to a stay-at-home significant other. What said young workforce has in enthusiasm, cloying hyperbabble, and comfort with the cult of Bloomberg they lack in depth of knowledge. They talk quickly, and generally know answers to specific questions, but don't understand systems from the runtime environment all the way down to bare metal. Management actually get angry if you question design decisions or spend time cleaning up code. Expect to be micromanaged and constantly berated with a stern "Why are you doing that?" at least ten times a day. The HR department is a travesty. The "Bloomberg" recruiters are contractors who then find other contractors. If you work as a contractor, expect absolutely no follow-up on questions to HR and to never, ever be able to get in touch with HR people, particularly the "senior" contracted HR recruiters. Like normal HR, they strive to keep the best talent out and consistently work half days. You're stuck trying to figure out even simple things for yourself. Basically, if you think for yourself, aren't willing to march to orders no matter how irrational they are, and have talent, you'll either be turned down or shown the door quickly with the Scarlet Letter rendering you unfit to ever work at Bloomberg again. HR is also very secretive and getting straight answers for important decisions is wasted effort. I've also heard stories that certain HR recruiters will lie in order to steer business toward specific vendors -- this is just speculation.